A Compact Wideband Vertically Polarized End-Fire Millimeter-Wave Antenna Utilizing Slot, Dielectric, and Cavity Resonators

A compact wideband vertically polarized endfire antenna operating at millimeter-wave (mmWave) is proposed. The wideband characteristic is achieved by combining three resonances which are, respectively, formulated using slot, dielectric, and cavity resonators. The compact topology is realized through the employment of dielectric loading technique. The proposed via-structured antenna element is designed to operate from 25.8 to 40.1 GHz, which represents a bandwidth of 43.4%. The antenna features a compact size of 0.37\times 0.45\times 0.17\,\,\lambda _{\mathrm {max}}^{3} ( 4.3\times 5.2\times 2 mm3), where \lambda _{\mathrm {max}} is the free-space wavelength at the lowest frequency. The element realized gain varies from 3.5 to 7.6 dBi. A detailed performance analysis is provided, which helps to understand the principle of operation of the proposed antenna. The dielectric situated in the frontside of the cavity features a dual-function: 1) a resonator to generate the second resonance and 2) an impedance matching layer for the entire operating band. Two antenna array models are fabricated and examined for in-depth investigation. The first model contains a power divider for fixed beam analysis, and the second model is connected to the mmWave beamforming module to investigate the beam scanning capability of the proposed antenna. The simulated impedance bandwidth (reflection coefficient < -10 dB) of the four-element array equals 47.1% from 24.75 to 40 GHz and the realized gain varies from 6 to 11.4 dBi. The studies collectively ascertain that the proposed antenna features one of the most compact volumes while exhibiting one of the widest bandwidths to be reported in the literature.